The present invention relates generally to seat cushions and, more specifically, to seat cushions used in buses or other large passenger vehicles.
At present, seats for vehicles can be manufactured by assembling a cushioned cover on a seat frame, such as the frame of a school bus seat. The cushioned cover is often formed by creating a foam envelope, The foam envelope can be created by first cutting or slicing foam into a predetermined thickness and into a front piece, back piece, and outer strip. The strip is located between the front and back pieces and laminated with an adhesive to create the foam envelope having a cavity or envelope shape, which is configured to cover the seat frame when installed.
Additional materials may be added to the foam envelope. For example, Styrofoam kneepads can be added to enhance critical impact areas, e.g., where a passenger's knee may come into contact with the cushioned cover. Additionally, fabric can be added to critical seams to add to quality and longevity of the foam envelope.
After the foam envelope has been formed, it is fitted over the seat frame. A vinyl seat cover is then be placed over the foam envelope to assist in compartmentalization and to create a flame retardant barrier. The addition of the seat cover is typically required to meet regulations, such as FMVSS 222 and FMVSS 302 for school buses.
The seat can provide a higher level of safety by creating compartmentalization. More specifically, the seat is configured to maintain the occupant within a particular space or compartment. The compartmentalization can be enhanced by using a high-back, well-padded seat designed for specific crash standards.
The seat also should meet specific flammability standards. However, if the outer vinyl cover becomes damaged (e.g., due to vandalism), additional oxygen flow is permitted within the seat. In the event of fire, the additional oxygen flow can increase the heat beyond the flash point of the foam and cause the seat to burn, thereby increasing the potential for fires to spread within the bus.
In the conventional design, the foam envelope may break down within the vinyl cover and the seat frame can become exposed. This can compromise the protection level provided by the foam. Additionally, the intended compartmentalization may become compromised.